Headrest cushions are well-known and exist in many varieties. The goal in improvements of these devices and their systems is to make an apparatus that is comfortable, relatively easy to maintain and operate, and inexpensive to manufacture. A few examples of headrest cushions that exist in the art include: Harnish, U.S. Pat. No. 5,345,633, which discloses a cushion for supporting a person's neck that can be detachably secured to a seat back of an automobile or other vehicle by a pair of straps; Rossini, U.S. Pat. No. 5,503,456, which discloses a pillow comprising an insert and a case which can be secured to the back of a lawn chair with three stretchable straps; and Chow, U.S. Pat. No. 5,544,378, which discloses an inflatable pillow provided with strap means to secure the assembly to a back rest. The adjustable cushioned headrest of my invention adds to this art through a novel method of securing the cushion to a seat back in such a manner that the position of the cushion may be adjusted vertically while the assembly is secured to the seat back. My invention adds further to the art through its novel means of adjusting the size of the cushion receiving means thereby enabling the assembly to easily receive different sized cushions.